1. Field of the Invention
The present invention relates an electrical connecting member, and an electric circuit member wherein parts of an electric circuit are connected to a substrate and the like through the electrical connecting member.
2. Related Background Art
In the past, the connection between a substrate such as a circuit board and parts of an electric circuit was effected by using a connector method, press-fit terminal method, soldering method, wire bonding method, TAB (tape automated bonding) method, CCB (controlled collapsed bonding) method, or a method utilizing anisotropy conductive film. However, in such methods, since minimum pitches between adjacent connecting portions for preventing them from contacting with each other were relatively great, even if the smaller pitches between the adjacent connecting portions were required, such requirements could not be satisfied. Further, in such methods, since the longer wiring was required, the resistance value and the stray capacity were increased to deteriorate the electrical feature.
In order to solve the above problems, a technique wherein electric circuit parts are electrically connected to each other by means of an electrical connecting member comprising a plurality of conductive members electrically insulated from each other and held in an insulative holder or by means of an electrical connecting member comprising connecting conductive members wired in and/or on an insulative holder and having both ends exposed on the insulative holder with being flush with or protruding from the both surfaces of the insulative holder has been proposed, as disclosed in the Japanese Patent Laid-Open Nos. 63-222437 and 63-224235.
FIGS. 1A and 1B schematically, in section, show the electrical connection between the electric circuit parts effected by using such electrical connecting member.
In FIGS. 1A and 1B, the reference numeral 1 denotes the electrical connecting member; and 2 denotes the electric circuit parts to be connected. The electrical connecting member 1 comprises a plurality of rod-like conductive members 4 made of metal or alloy and electrically insulated from each other and embedded in a thin plate-shaped holder 5 made of electrically insulative material. Both ends of each conductive member 4 are protruded towards the electric circuit parts 2 and 3 as bumps 8 and 9, respectively (see FIG. 1A).
Connecting portions 6 of the electric circuit part 2 and the bumps 8 of the conductive members 4, and connecting portions 7 of the electric circuit part 3 and the bumps 9 of the conductive members 4 are, respectively, connected to each other by metalizing and/or alloying them, for example, by means of thermal pressure welding process or ultrasonic heating process, thus electrically connecting the electric circuit parts 2 and 3 to each other (see FIG. 1B).
By the way, as a method for manufacturing the above-mentioned electrical connecting member 1, a method shown in FIGS. 2A to 2E has been proposed.
In this method, first of all, a photosensitive resin layer 11 acting as the holder 5 is coated on a conductive copper foil 10 (see FIG. 2A). Then, holes 12 are formed in the photosensitive resin layer 11 to expose the copper foil 10, by exposing and developing the layer at predetermined positions where the conductive members 4 are embedded at a later process. Then, by increasing the temperature, the photosensitive resin layer 11 is cured (see FIG. 2B). Thereafter, by etching the copper foil 10 exposed through the holes 12, recesses 13 are formed in the copper foil 10 under the holes 12 (see FIG. 2C). Then, the conductive members 4 are filled within the holes 12 and the recesses 13 by electroplating the copper foil 10 with metal so that the bumps 9 are formed in the recesses 13 and the bumps 8 are formed on the photosensitive resin layer 11 (see FIG. 2D). Thereafter, by removing the copper foil 10 by means of metal etching process, the electrical connecting member 1 is completed (see FIG. 2E).
However, in the method for connecting the connecting portions of the electric circuit parts to the bumps of the conductive members by metalizing and/or alloying them by means of the thermal pressure welding process or the ultrasonic heating process as shown in FIG. 1, since the electric circuit parts are exposed to heat during the connecting operation, if such parts have low heat-resistance, they cannot sometimes be connected.
By the way, a method for obtaining the electrical connection by relatively low temperature welding process, rather than the high temperature heating process is already known (refer to the Japanese Patent Laid-Open No. 63-151031). In this method, the electrical connection is obtained by positioning and pressure welding electrodes disposed on a circuit board and coated by ultraviolet radiation cured resin and electrodes of semi-conductor elements with bumps and by curing the resin by means of the ultraviolet radiation. However, in this method, it is difficult to compose the resin, and, therefore, there arise many problems to obtain the desired resin. Further, since the resin is liable to be existed in the connecting portions, the connecting resistance is increased and/or the difference in the coefficient of thermal expansion is increased, thus arising the quality problem. Further, since there exists the resin between the adjacent connecting portions, the difference in the coefficient of thermal expansion is increased, thus arising the quality problem that the connecting portions are separated and/or the crack is generated.